Think That Medium-Rare Chicken Liver Is Safe? Think Again

god of food" David Chang asked, "Can someone explain why chicken liver cooked medium rare is OK, but rest of bird must be cooked well done? #nonsensical." It was a while back, but as I remember he never got a response that fully satisfied him. That's probably because there is no such answer: A report out today from the Centers for Disease Control and Prevention indicates strongly that undercooked chicken livers aren't safe at all.

At first glance, the report seems to be something we here in California can ignore. The headline, "Multistate Outbreak of Campylobacter jejuni Infections Associated with Undercooked Chicken Livers -- Northeastern United States, 2012," seems to be referring to a long-ago outbreak of something or other somewhere on the other side of the country. But read a little further and it becomes clear that this is not an isolated issue, and in fact tells us that just like every other part of the chicken, the liver must be fully cooked to be safe.

It appears that the outbreak in question probably only seems isolated because "Vermont is one of the few states that investigates all reported cases of campylobacteriosis," and that "These outbreaks should not come as a surprise, given that previous studies have shown that 77% of retail chicken livers are contaminated with Campylobacter and that, when contamination is present, it is usually in internal tissues, as well as on the surface." It goes on to say:

Studies outside the United States have found that, in order for chicken livers to be free of Campylobacter, they must be heated to internal temperatures in excess of 158 F (70 C) and held at that temperature for 2-3 minutes. In this investigation, the livers were found to be intentionally cooked lightly to maintain a desired texture and taste. This practice might be common, particularly when preparing chicken livers for use in a mousse or pâté. A popular recipe for this dish instructs readers to cook "until the livers are just stiffened, but still rosy inside."

Indeed, when I cook livers at home, the desired outcome is a sear on the outside and a creamy, rosy center. I've often wondered the same thing as Chang -- how is this not just undercooked chicken? Why isn't it just as dangerous? Certainly the aesthetic appeal of medium-rare chicken thigh isn't the same as a nice pink chicken liver, but scientifically it seemed odd.

Just for reference: Campylobacter jejuni is the third-leading cause of bacterial foodborne illness in the United States, and causes abdominal pain, diarrhea and fever. It can be severely debilitating but is rarely life-threatening.